AU2007332134B2

AU2007332134B2 - Slotting machine

Info

Publication number: AU2007332134B2
Application number: AU2007332134A
Authority: AU
Inventors: Johann Friederich Jaeggi; Klaus Juergen Roeske
Original assignee: Bishop Innovation Pty Ltd
Current assignee: Bishop Innovation Pty Ltd
Priority date: 2006-12-12
Filing date: 2007-12-04
Publication date: 2013-02-21
Anticipated expiration: 2027-12-04
Also published as: WO2008070899A1; AU2007332134A1

Abstract

A machine for cutting an array of longitudinally extending slots in the bore of a sleeve. The machine comprises two spaced apart work holding devices, each adapted to hold and index a sleeve, an oscillating cutting spindle, and a cutting tool mounted on the cutting spindle. The arrangement of the machine is such that the cutting tool is able to cut the longitudinally extending slots in a sleeve held by either one of the work holding devices whilst another sleeve is loaded into the other work holding device.

Description

WO 2008/070899 PCT/AU2007/001861 1 SLOTTING MACHINE TECHNICAL FIELD 5 The present invention relates to a machine and method for cutting an array of longitudinally extending slots in the bore of a sleeve, and more particularly in the bore of a sleeve for a hydraulic power steering valve. BACKGROUND 10 Vehicle hydraulic power steering systems are typically controlled by rotary valves. This type of valve has a sleeve with an array of longitudinally extending slots in its bore. These slots are commonly arcuate, as described in US Patent 3,591,139 (Bishop). Usually the slots are blind ended, but in some designs they extend to the 15 end of the sleeve to provide a return path for hydraulic fluid. US Patent 5,292,214 (Bishop) discloses a machine for cutting arcuate slots in the bore of a sleeve. The sleeve is held in an indexable work holding device whilst the slots are cut using a finger like cutting tool. The cutting tool is mounted on a cutting 20 spindle that oscillates about its axis by means of a crank mechanism. The cutting spindle is carried by a capsule that includes a desmodromic cam mechanism to retract the tool from the slot at the bottom of each cutting stroke. The cutting capsule is movable relative to the work holding device to feed the tool as it cuts a slot, with the work holding device indexing the sleeve between slots. The work holding spindle 25 moves downwards and the cutting capsule moves aside to provide access for unloading and loading a sleeve into the work holding spindle. Sleeves for hydraulic power steering valves usually have a drive pin hole (or slot) in the side of the sleeve to rotationally connect the sleeve to the pinion or worm of the 30 steering gear. The sleeve slots must be angularly oriented to the drive pin hole. This can be achieved by orienting the sleeve such that the drive pin hole points in the correct direction before the sleeve is loaded into the work holding device. Alternatively, the sleeve can be oriented after it is loaded into the work holding device by detecting WO 2008/070899 PCT/AU2007/001861 2 the drive pin hole as the sleeve is rotated by the work holding device. A probe that contacts the sides of the drive pin hole as the sleeve is rotated in both directions may be used for this purpose. 5 US Patent 5,390,408 (Bishop et al) discloses a machine that both cuts the slots in the bore of a sleeve and machines the bore of the sleeve. To machine the bore, the work holding device rotates the sleeve whilst the sleeve is moved relative to a boring tool. For maximum accuracy, the sleeve is not released by the work holding device between the slotting and boring operations. A method of using such a machine is 10 disclosed in US Patent 6,032,350 (Roeske). The method comprises cutting the slots in a sleeve, boring the sleeve, and then passing a cutting tool through the slots again to remove any burr pushed into the slots by boring. US Patent 6,203,258 (Scott) discloses a machine for cutting slots in the bore a sleeve 15 in which two opposed, finger like cutting tools are mounted on the same cutting spindle. This arrangement has several uses. For instance, the two cutting tools may have different widths to cut different width slots, or the two cutting tools may be adapted to cut slots of different radius. 20 Sleeves for power steering valves are typically made in very large quantities. As such, it is desirable for a machine for slotting sleeves to be highly productive, and it is particularly desirable that the cycle time be as low as possible. It is an object of the present invention to provide a machine for cuffing an array of longitudinally extending slots in the bore of a sleeve having improved productivity. 25 SUMMARY OF INVENTION In a first aspect, the present invention consists of a machine for cutting an array of longitudinally extending slots in the bore of a sleeve, the machine comprising a first 30 work holding device adapted to hold and index the sleeve, a cutting spindle movable relative to the first work holding device, the cutting spindle being adapted to oscillate about its axis, and at least one cutting tool mounted on the cuffing spindle, the cuffing tool being adapted to cut the longitudinally extending slots, characterised in that the WO 2008/070899 PCT/AU2007/001861 3 machine further comprises a second work holding device offset from the first work holding device and adapted to hold and index the sleeve, the cutting spindle being movable relative to the first and second work holding devices such that the cuffing tool is able to cut the longitudinally extending slots in a sleeve held by either one of 5 the first and second work holding devices whilst another sleeve is loaded into the other work holding device. Preferably the machine further comprises at least one drilling device adapted to drill a hole in the side of a sleeve whilst the sleeve is held by one of the first and second 10 work holding devices. Preferably the machine further comprises a reaming device adapted to ream the hole drilled by the drilling device. 15 Preferably at least one of the first and second work holding devices is adapted to move a sleeve held by it along the axis of the sleeve. Preferably the first and second work holding devices are mounted on a common machine base, and the cutting spindle is carried by a capsule mounted on a slideway 20 attached to the common machine base. Preferably the machine further comprises a boring tool movable with the cuffing spindle, at least one of the first and second work holding spindles being adapted to rotate and axially feed a sleeve relative to the boring tool to machine the bore of the 25 sleeve. Preferably the machine further comprise a bore measuring device adapted to check that the size of a sleeve bore machined by the boring tool is within specified limits. 30 Preferably the machine further comprises at least one orientation device associated with at least one of the first and second work holding devices, the orientation device comprising a probe adapted to contact the sides of a hole in a sleeve held by the associated work holding device as it rotates the sleeve in either direction.

WO 2008/070899 PCT/AU2007/001861 4 Preferably the at least one cutting tool comprises first and second opposed cutting tools. In one preferred embodiment the first and second cutting tools are adapted to cut slots of different width. In another preferred embodiment the first and second 5 cutting tools are adapted to cut slots of different radius. Preferably the machine further comprises a loading apparatus, the loading apparatus comprising a first gripper movable such that it can pick up a sleeve at a first fixed location and load it into either of the first and second work holding devices, and a 10 second gripper movable such that it can pick up a sleeve from either of the first and second work holding devices and place it at a second fixed location. Preferably the sleeve is a component of a hydraulic power steering valve. 15 In a second aspect, the present invention consists of a method of manufacturing a sleeve for a hydraulic power steering valve, the method comprising cutting an array of longitudinally extending slots in the bore of the sleeve using a machine comprising a first work holding device adapted to hold and index the sleeve, a cutting spindle movable relative to the first work holding device, the cutting spindle being adapted to 20 oscillate about its axis, and at least one cutting tool mounted on the cutting spindle, the cutting tool being used to cut the longitudinally extending slots, characterised in that the machine further comprises a second work holding device offset from the first work holding device and adapted to hold and index the sleeve, the cutting spindle being movable relative to the first and second work holding devices such that the 25 cutting tool is able to cut the longitudinally extending slots in a sleeve held by either one of the first and second work holding devices, the method further comprising loading the sleeve into one of the work holding devices whilst the cutting tool cuts an array of longitudinally extending slots in another sleeve held by the other work holding device. 30 Preferably the method further comprises drilling a drive pin hole in the sleeve after it is loaded into one of the work holding devices.

WO 2008/070899 PCT/AU2007/001861 5 BRIEF DESCRIPTION OF DRAWINGS Fig. 1 is a sectional view of a typical sleeve for a hydraulic power steering valve. 5 Fig. 2 shows the motion of a typical cutting tool culling the slots in the bore of a sleeve. Fig. 3 shows a first preferred embodiment of a machine for cutting slots in the bore of a sleeve, in accordance with the present invention. 10 Fig. 4 shows the machine of Fig. 3 in a different position. Fig. 5 is a detail, partially sectioned view of the machine of Fig. 3 showing slots being cut in a sleeve. 15 Fig. 6 is a detail side view of the machine of Fig. 3 showing the slots being cut in a sleeve. Fig. 7 is a detail, partially sectioned view of the machine of Fig. 3 showing a sleeve 20 being oriented prior to slotting. Fig. 8 is a detail view of the machine of Fig. 3 showing a sleeve being approximately oriented prior to loading into one of the work holding devices. 25 Fig. 9 shows a second preferred embodiment of a machine in accordance with the present invention, having two cutting tools and a boring tool. Fig. 10 shows a third preferred embodiment of a machine in accordance with the present invention, having a drilling device. 30 WO 2008/070899 PCT/AU2007/001861 6 BEST MODE OF CARRYING OUT THE INVENTION Fig. 1 shows a typical sleeve 1 for a hydraulic power steering valve. Sleeve 1 has an array of longitudinally extending slots 2 in its bore 3. Sleeve 1 has eight slots 2 but the 5 number of slots can vary in other sleeve designs. Slots 2 are arcuate and blind ended. In operation of the valve, hydraulic fluid flows through holes 4 in a well known manner. The skirt 5 of sleeve 1 has a drive pin hole 6 extending through it, and slots 2 are angularly oriented to the drive pin hole 6. 10 Fig. 2 shows a typical finger like cutting tool 11 that is utilised by the present invention, cutting the slots 2 of sleeve 1. Cuffing tool 11 has a replaceable carbide cutting insert 12. Cuffing tool 11 is shown at the bottom of its cutting stroke and it oscillates about axis 13 as indicated by the broken outline of tool 11. Cutting tool 11 is progressively fed into the bore 3 of sleeve 1 as it cuts, and it is usually retracted after each cuffing 15 stroke so it is clear of the slot 2 it is cutting on the return stroke. Cutting tool 11 cuts each of the slots 2 in turn and sleeve 1 is indexed between cutting each slot 2. The drive pin hole 6 is usually formed before cutting the slots 2 so they can be oriented correctly to drive pin hole 6. 20 Figs. 3 and 4 show a first preferred embodiment of a machine 10 for cutting the slots 2 in the bore 3 of a sleeve 1, in accordance with the present invention. Details of the machine, such as linear axes, bearings, servo systems, actuators, etc, are not shown as the implementation of these features is well understood by those skilled in the art of machine design. Furthermore, details of some features of the machine are given by 25 the referenced prior art where applicable. Machine 10 comprises a single cutting spindle 15 and two identical work holding devices 16. Work holding devices 16 are offset from each other with their axes 18 parallel, and are both mounted on a common machine base 17. 30 Referring to Figs. 5 and 6, each work holding device 16 has a work holding spindle 20, a collet 21 to grip a sleeve 1 in spindle 20, and a stop tube 22 to set the correct height of a sleeve 1 with respect to spindle 20. Spindle 20 is movable vertically to raise and WO 2008/070899 PCT/AU2007/001861 7 lower a gripped sleeve 1, by means of a servo motor 23 (refer to Fig. 3). Figs. 5 and 6 show spindle 20 in its raised position that is used for cutting slots 2. Spindle 20 is also rotatable to index a gripped sleeve 1, by means of another servo motor 24 (refer to Fig. 3). Collet 21 is opened and closed by an actuator 25 (refer to Fig. 3). 5 A cutting tool 11 is mounted on the cutting spindle 15. Cutting tool 11 cuts slots 2 as described above with reference to Fig. 2. Cutting spindle 15 is carried by a capsule 27 and it oscillates about its axis 13 by means of a crank mechanism inside capsule 27 (not shown). Cutting tool 11 is retracted during each return stroke by a desmodromic 10 cam mechanism also inside capsule 27 (not shown). Such a crank mechanism and desmodromic cam mechanism are described in US Patent 5,292,214 (Bishop). Referring again to Figs. 3 and 4, capsule 27 is mounted on a slideway 28 that is movable horizontally to any position within its operating range by a servo motor 29. 15 Slideway 28 has sufficient operating range to move cutting spindle 15 such that it can be used to cut the slots 2 in a sleeve 1 held by either work holding device 16. Fig. 3 shows cutting spindle 15 in a position to cut the slots 2 in a sleeve 1 held by the left hand side work holding device 16, and Fig. 4 shows cutting spindle 15 in a position to cut the slots 2 in a sleeve 1 held by the right hand side work holding device 16. When 20 cutting the slots 2 of a sleeve 1 held by one of the work holding devices 16, slideway 28 is used to move cutting spindle 15 relative to that work holding device 16 to feed the cutting tool 11 as it cuts. The work spindles 20 are lowered when the cutting spindle 15 moves from one work holding device 16 to the other to provide clearance for the cutting tool 11 and to allow cutting spindle 15 to continue to oscillate as it 25 moves. A loading apparatus 31 loads and unloads sleeves 1 into and out of the two work holding devices 16. A load conveyor 32 transports sleeves 1 to be slotted to a fixed loading location 33, and an unload conveyor 34 transports slotted sleeves 1 away 30 from a fixed unloading location 35. The loading apparatus 31 has a load gripper 37 and a unload gripper 38. Each gripper 37, 38 has a pair of fingers 42 to grip the inside of the skirt 5 of a sleeve 1.

WO 2008/070899 PCT/AU2007/001861 8 The load gripper 37 is attached to the end of a load actuator 39 such that it can move up and down. The unload gripper 38 is attached to the end of an unload actuator 41 such that it can also move up and down. Actuators 39 and 41 are preferably two position air cylinders. The load gripper 37 is also rotated by a rotary actuator 40 5 attached to the load actuator 39. The rotary actuator 40 is driven by a servo motor (not shown) so it can rotate the load gripper 37 to any position. Actuators 39 and 41 are carried by a load carriage 44 and a unload carriage 45 respectively. Carriages 44 and 45 are independently horizontally movable along a 10 gantry 46 by means of servo motors (not shown). The load carriage 44 has a horizontal range of travel sufficient for the load gripper 37 to pick up a sleeve 1 at the loading location 33 and load it into either work holding device 16. The unload carriage 45 has a horizontal range of travel sufficient for the unload gripper 38 to pick up a sleeve from either work holding device 16 and place it at the unloading location 35. 15 Fig. 3 shows the loading gripper 37 picking up a sleeve 1 from the loading location 33 whilst the unload gripper 38 is positioned above the left hand work holding device 16, waiting to unload a slotted sleeve 1. Fig. 4 shows the loading gripper 37 positioned above the left hand work holding device 16, having just loaded a sleeve, whilst the unload gripper 38 places a slotted sleeve 1 at the unloading location 35. 20 Sleeves 1 to be slotted arrive at the loading location 33 with their drive pin holes 6 pointing in random directions. The load gripper 37 picks up a sleeve 1 from the loading location 33 and firstly transports it next to a fixed pre-orientation probe 47, as shown in Fig. 8. The pre-orientation probe 47 is a non-contact probe, such as an 25 inductive probe. A gripped sleeve 1 is approximately oriented by the rotary actuator 40 rotating it until the pre-orientation probe 47 detects the drive pin hole 6. The load gripper 37 then loads the sleeve 1 into one of the work holding devices 16 with its drive pin hole 6 pointing to the right. 30 Referring to Fig. 7, a sleeve 1 is loaded into a work holding device 16 with its work spindle 20 lowered. Each work holding device 16 has an associated orientation device 49 comprising a probe 50, a switch 51, an actuator 52 and a slideway 53. The actuator 52 moves the tip of the probe 50 into the drive pin hole 6 of a loaded sleeve WO 2008/070899 PCT/AU2007/001861 9 1. The work spindle 20 then rotates one direction until the probe 50 contacts one side of the drive pin hole 6, which triggers the switch 51. The work spindle 20 then rotates in the other direction until the other side of the drive pin hole 6 contacts the probe 50 and triggers the switch 51 again. The rotation angles of the work spindle 20 at which 5 the switch 51 triggered are used to calculate the exact orientation of the drive pin hole 6 and the work spindle 20 then rotates a small amount as necessary to correct the orientation before cutting slots 2. The overall arrangement of machine 10 is such that a sleeve 1 can be unloaded, and 10 another sleeve 1 loaded and oriented, in either one of the work holding devices 16 whilst the slots 2 are being cut in a sleeve 1 held by the other work holding device. The cutting spindle 15 is thereby fully utilised because it does not have to wait for a work holding device to be loaded or unloaded. As such, the machine 10 provides reduced cycle time and improved productivity compared with prior art machines 15 having only a single work holding device. Fig. 9 shows a second preferred embodiment of a machine 1 0a in accordance with the present invention. Machine 10a is the same as machine 10 described above except that machine 1 Oa has two opposed cutting tools 11 a and 11 b mounted on its 20 cutting spindle 15a, and a boring tool 55. Boring tool 55 is mounted on the capsule 27 such that it is movable horizontally with cutting spindle 15a. The boring tool 55 has a single cutting tip 56 and is used to machine the bore 3 of a sleeve 1 in a similar manner to that described in US Patent 5,390,408 (Bishop et al). During the boring operation, the work holding spindle 20 rotates at high speed to rotate the sleeve 1 25 whilst the work holding spindle 20 simultaneously moves vertically to feed the cutting tip 56 along the bore 3. Capsule 27 is moved horizontally to control the depth of cut. A bore measuring device (not shown) may be provided to check that the size of the machined bore 3 is within specified limits. The bore measuring device may comprise 30 an air gauge carried by the unload carriage 45 that extends down into the bore 3 after the boring operation whilst the sleeve 1 is still held by a work holding device 16.

WO 2008/070899 PCT/AU2007/001861 10 The opposed cutting tools 11 a and 11 b may be used in a number of different ways depending on the application, as described in US Patent 6,203,258 (Scott). For example, cutting tools 11 a and 11 b may be adapted to cut slots of different radius, or they may be adapted to cut slots of different width. In other applications, one of the 5 tools 11 a, 11 b may have a cutting tip adapted to cut a convex shaped slot that breaks out the end of the sleeve. Machine 10a may also be used to implement a method of reducing burrs on the sides of the slots 2 as described in US Patent 6,032,350 (Roeske). This method involves a 10 first slot cutting operation to cut slots 2 using one of the cutting tools 11 a, 11 b, then a boring operation to finish the bore 3 using the boring tool 55, and then a second slot cutting operation to cut the same slots 2 a second time to remove the burr generated by boring. The second slot cutting operation may use the other one of the cutting tools 11 a, 11 b than was used for the first slot cutting operation, in which case the second 15 cutting tool used will preferably cut the slots 2 slightly wider than produced by the first cutting operation, or the second cutting operation can be performed using the same cutting tool 11 a, 11 b as the first cutting operation. In other not shown embodiments of the present invention, two opposed cutting tools 20 11 a and 11 b may be provided on a machine without a boring tool 55, or a boring tool 55 may be provided on a machine with only one cutting tool 11 mounted on its cutting spindle 15. In other not shown embodiments of the present invention, the work spindles 20 may be fed axially during the slot cutting operation to cut slots that break out the end of the sleeve, as described in US Patent 6,082,940 (Roeske). 25 Fig. 10 shows a third preferred embodiment of a machine 10b in accordance with the present invention. Machine 1Ob is the same as machine 10 described above except that machine 10 b has a drilling device 58 associated with each work holding device 16, instead of an orientation device 49, and machine 10b does not have a pre 30 orientation probe 47. Sleeves 1 are loaded into machine 10b without drive pin holes 6. This means that it is not necessary to orient the sleeves 1 before cutting the slots 2. Instead, the sleeves are loaded into the work holding devices 16 in a random orientation and then the drive pin holes 6 are drilled by the drilling devices 58, either WO 2008/070899 PCT/AU2007/001861 11 before or after cuffing slots 2. The sleeve 1 is not released between drilling the drive pin hole 6 and cuffing the slots 2, so correct orientation is ensured. Each drilling device 58 comprises a drill bit 59 gripped in a rotating chuck 60 and a means to feed the chuck 60 axially. Drilling devices 58 for drilling drive pin holes 6 are particularly 5 suited to embodiments of machines in accordance with the present invention that utilise the method of reducing burrs described above because the increased cycle time required for slotting, burring and slotting at one work holding device 16 can be partly balanced by the increased cycle time required for drilling the drive pin hole 6 at the other work holding device 16. 10 In other not shown embodiments of the present invention, each work holding device 16 may have two drilling devices 58 associated with it. In such an arrangement, one of the drilling devices 58 has a drill bit 59, as shown in Fig. 10, and the other drilling device 58 has a reamer instead to finish the drive pin hole 6 after it is drilled by the 15 first drilling device 58. The two drilling devices 58 are rotationally offset from each other so that after the first drilling device 58 has drilled the drive pin hole 6, the work holding spindle 20 is rotated to align the hole 6 with the second drilling device 58. The term "comprising" as used herein is used in the inclusive sense of "including" or 20 "having" and not in the exclusive sense of "consisting only of'.

Claims

1. A machine for cutting an array of longitudinally extending slots in the bore of a sleeve, the machine comprising a first work holding device adapted to hold and 5 index the sleeve, a cutting spindle movable relative to the first work holding device, the cutting spindle being adapted to oscillate about its axis, and at least one cutting tool mounted on the cutting spindle, the cutting tool being adapted to cut the longitudinally extending slots, characterised in that the machine further comprises a second work holding device offset from the first work holding device 10 and adapted to hold and index the sleeve, the cutting spindle being movable relative to the first and second work holding devices such that the cutting tool is able to cut the longitudinally extending slots in a sleeve held by either one of the first and second work holding devices whilst another sleeve is loaded into the other work holding device. 15

2. A machine as claimed in claim 1 further comprising at least one drilling device adapted to drill a hole in the side of a sleeve whilst the sleeve is held by one of the first and second work holding devices. 20

3. A machine as claimed in claim 2 further comprising a reaming device adapted to ream the hole drilled by the drilling device.

4. A machine as claimed in claim 1 wherein at least one of the first and second work holding devices is adapted to move a sleeve held by it along the axis of the sleeve. 25

5. A machine as claimed in claim 1 wherein the first and second work holding devices are mounted on a common machine base, and the cutting spindle is carried by a capsule mounted on a slideway attached to the common machine base. 30 WO 2008/070899 PCT/AU2007/001861 13

6. A machine as claimed in claim 1 further comprising a boring tool movable with the cutting spindle, at least one of the first and second work holding spindles being adapted to rotate and axially feed a sleeve relative to the boring tool to machine the bore of the sleeve. 5

7. A machine as claimed in claim 6 further comprising a bore measuring device adapted to check that the size of a sleeve bore machined by the boring tool is within specified limits. 10

8. A machine as claimed in claim 1 further comprising at least one orientation device associated with at least one of the first and second work holding devices, the orientation device comprising a probe adapted to contact the sides of a hole in a sleeve held by the associated work holding device as it rotates the sleeve in either direction. 15

9. A machine as claimed in claim 1 wherein the at least one cutting tool comprises first and second opposed cutting tools.

10. A machine as claimed in claim 9 wherein the first and second cutting tools are 20 adapted to cut slots of different width.

11. A machine as claimed in claim 9 wherein the first and second cutting tools are adapted to cut slots of different radius. 25

12. A machine as claimed in claim 1 further comprising a loading apparatus, the loading apparatus comprising a first gripper movable such that it can pick up a sleeve at a first fixed location and load it into either of the first and second work holding devices, and a second gripper movable such that it can pick up a sleeve from either of the first and second work holding devices and place it at a second 30 fixed location.

13. A machine as claimed in claim 1 wherein the sleeve is a component of a hydraulic power steering valve. WO 2008/070899 PCT/AU2007/001861 14

14. A method of manufacturing a sleeve for a hydraulic power steering valve, the method comprising cutting an array of longitudinally extending slots in the bore of the sleeve using a machine comprising a first work holding device adapted to hold 5 and index the sleeve, a cutting spindle movable relative to the first work holding device, the cutting spindle being adapted to oscillate about its axis, and at least one cutting tool mounted on the cutting spindle, the cutting tool being used to cut the longitudinally extending slots, characterised in that the machine further comprises a second work holding device offset from the first work holding device 10 and adapted to hold and index the sleeve, the cutting spindle being movable relative to the first and second work holding devices such that the cutting tool is able to cut the longitudinally extending slots in a sleeve held by either one of the first and second work holding devices, the method further comprising loading the sleeve into one of the work holding devices whilst the cutting tool cuts an array of 15 longitudinally extending slots in another sleeve held by the other work holding device.

15. A method of manufacturing a sleeve for a hydraulic power steering valve as claimed in claim 14 further comprising drilling a drive pin hole in the sleeve after it 20 is loaded into one of the work holding devices.